Describe how you would create a model of sea-floor spreading using everyday materials

Take a cardboard, cylinder-shaped container and cut a vertical slit about 3 ½ inches long and ¼ inch wide down the side. The slit is your mid-ocean ridge, the place where the plates are moving away from each other.

Cut a piece of white paper in half lengthwise.

On each piece of paper, measure two inches in from the end and fold the paper so that there is a section on each end to hold onto.

Measure inward another two inches from the fold, and color in that two-inch wide strip.

Continue to measure in two-inch segments, coloring every other section.

Place the unfolded ends of the paper into the slit in the container. Holding them by the folds, pull the pieces of paper out again. If you imagine that the slit is the midocean ridge where the plates are moving away from each other, the paper is the new liquid rock coming out from the ridge. The first bit of paper to come out is the oldest rock, and the last section of paper to come out is the youngest. Imagine that your paper goes on forever. Soon, the first bit you took out of the hole will be far away from the midocean ridge. Of course, “soon” in geological time is a very long time in human terms!

Take your pieces of paper and tape the ends that aren’t folded to the pencil.

Put the pencil inside of the container and pull the ends of the pieces of paper up through the slit.

Twist the pencil one way, and the papers will move out and away from each other. This is what happens at a divergent plate boundary on the mid-ocean ridges.

Twist the pencil the other way, and the papers will move in and toward each other. This is what happens at a convergent plate boundary. Imagine what would happen if those papers had bumps on them. They’d get all bunched together at the hole, and create mountains.

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